1. Field of the Invention
The present invention relates generally to electrical circuitry and, more particularly, to a technique for packaging electronic devices using a combination wirebond I/O and thru via interconnect process.
2. Description of the Related Art
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Packaging of electrical circuits is a key element in the technological development of any device containing electrical components. Fine-Pitch Surface Mount Technology (FPT) and Pin-Grid Array (PGA) technology are well developed areas of packaging technology. An emerging packaging method has been developed using Ball Grid Array (BGA) technology. BGA packages implement conductive metal, such as solder, which is formed into spheres or balls and disposed on conductive ball pads on a substrate or other surface. The solder balls are generally configured into an array to provide mechanical as well as electrical interfaces between surfaces, such as an integrated circuit die and a substrate, for instance.
BGA technology offers several advantages over FPT and PGA. Among the most often cited advantages of BGA are: reduced co-planarity problems, since there are no leads; reduced placement problems; reduced handling damage; smaller size; better electrical and thermal performance; better package yield; better board assembly yield; higher interconnect density; multi-layer interconnect options; higher I/Os for a given footprint; easier extension to multi-chip modules; and faster design-to-production cycle time. Despite the benefits provided by BGA technology, BGA is still a surface mount technology like FPT and PGA and, thus, is limited by the space available on the mounting surface.
Significant research and development has been devoted to finding ways to provide greater capabilities into smaller areas. One mechanism for increasing the amount of electrical circuitry without increasing the surface mount space necessary to house the components is to stack devices on top of each other. Circuit packages may be mounted one on top of the other using BGA technology. To couple each device to the underlying substrate, ball grid array technology may be used. However, stacking devices generally requires implementing different interconnect technologies to electrically couple die-to-die and die-to-substrate. Increasing the number of surface mount technologies may disadvantageously increase the failure rate of systems and unnecessarily complicate device design.
With die-to-die interconnects, there is less concern regarding mismatched coefficients of thermal expansion (CTE) since the die will expand and contract at a similar rate. Conversely, at the die-to-substrate interconnect there may be a significant CTE mismatch between the silicon die and the substrate material. This problem is often solved by using underfill. However, the process of implementing underfill is relatively expensive and time consuming. Further, die stacking using underfill may add stress to the package.
The present invention may address one or more of the problems set forth above.